The objectives of this project are to determine the primary, quaternary and possibly the tertiary structure of some of the initial enzymes concerned with the synthesis of heme, vitamin B12 and chlorophyll. Along with these studies we plan to continue our elucidation of some mechanisms in the synthesis of porphyrins and related compounds. Emphasis will be given to the enzyme delta-aminolevulinic acid dehydratase not only is it the first enzyme to catalyze the synthesis of an aromatic compound in the sequence but we have crystallized it from liver and have studied its quaternary structure chemically and by electron microscopy. Furthermore we plan to study the primary sequence of the peptide, having the amino group which forms a Schiff base with the substrate, of the enzymes isolated from various sources and the cation requirement of the enzymes from different sources. We plan to continue our studies on C13 and H1 magnetic resonance spectroscopy (NMR) on vitamin B12 in order to get some clue as to the mechanisms of formation of the functional isomer of the porphyrins. Also we plan to continue our synthesis of water insoluble enzyme derivatives of these enzymes in order to be able to synthesize quantities of the intermediates and of porphyrins having high concentrations of stable isotopes.